Many passenger seats such as those on passenger aircraft, buses, trains, and the like are intended to accommodate passengers in multiple positions or configurations. For example, some seat structural assemblies are designed for both sitting positions and lie-flat positions. However, because different seat surface contours are required for these positions, conventional seats require additional components such as additional and/or replaceable mattresses, contoured inserts, etc.
In certain situations, it may be desirable to design seats to adapt to sitting and lie-flat configurations without requiring replacement or additional components.